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Log warning instead of failing SDK when discovering dangling target. #6685

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merged 3 commits into from
Oct 9, 2020
Merged

Log warning instead of failing SDK when discovering dangling target. #6685

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244cd30
Log warning instead of failing SDK when discovering dangling target.
wu-hui Oct 7, 2020
4441306
Add unit test
wu-hui Oct 9, 2020
320cb53
Delete old test.
wu-hui Oct 9, 2020
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4 changes: 3 additions & 1 deletion Firestore/core/src/local/leveldb_target_cache.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -29,6 +29,7 @@
#include "Firestore/core/src/model/document_key_set.h"
#include "Firestore/core/src/nanopb/byte_string.h"
#include "Firestore/core/src/nanopb/reader.h"
#include "Firestore/core/src/util/log.h"
#include "Firestore/core/src/util/string_apple.h"
#include "absl/strings/match.h"

Expand Down Expand Up @@ -168,11 +169,12 @@ absl::optional<TargetData> LevelDbTargetCache::GetTarget(const Target& target) {
std::string target_key = LevelDbTargetKey::Key(row_key.target_id());
target_iterator->Seek(target_key);
if (!target_iterator->Valid() || target_iterator->key() != target_key) {
HARD_FAIL(
LOG_WARN(
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HARD_FAIL could not return, which effectively ensured that the loop terminated and that the target_iterator would be both valid and point to a record that matched target_key. Changing this to LOG_WARN allows the code to continue, breaking this condition.

I think the right thing to do is add a continue below this to avoid trying to parse target_iterator->value().

It's probably also worth adding a unit test to validate that this works. You can do this by writing a dummy row using LevelDbQueryTargetKey with a canonical ID that matches the query but has an invalid target ID.

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Done.

"Dangling query-target reference found: "
"%s points to %s; seeking there found %s",
DescribeKey(index_iterator), DescribeKey(target_key),
DescribeKey(target_iterator));
continue;
}

// Finally after finding a potential match, check that the target is
Expand Down
21 changes: 21 additions & 0 deletions Firestore/core/test/unit/local/leveldb_target_cache_test.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -17,6 +17,7 @@
#include "Firestore/core/src/local/leveldb_target_cache.h"

#include "Firestore/core/include/firebase/firestore/timestamp.h"
#include "Firestore/core/src/local/leveldb_key.h"
#include "Firestore/core/src/local/leveldb_persistence.h"
#include "Firestore/core/src/local/persistence.h"
#include "Firestore/core/src/local/target_data.h"
Expand Down Expand Up @@ -58,6 +59,10 @@ class LevelDbTargetCacheTest : public TargetCacheTestBase {
LevelDbTargetCache* leveldb_cache() {
return static_cast<LevelDbTargetCache*>(persistence_->target_cache());
}

LevelDbPersistence* leveldb_persistence() {
return static_cast<LevelDbPersistence*>(persistence_.get());
}
};

TEST_F(LevelDbTargetCacheTest, MetadataPersistedAcrossRestarts) {
Expand Down Expand Up @@ -130,6 +135,22 @@ TEST_F(LevelDbTargetCacheTest, RemoveMatchingKeysForTargetID) {
});
}

// We see user issues where target data is missing for some reason, and the root
// cause is unknown. This test makes sure the SDK proceeds even when this
// happens. See: https://github.com/firebase/firebase-ios-sdk/issues/6644
TEST_F(LevelDbTargetCacheTest, SurvivesMissingTargetData) {
persistence_->Run("test_remove_matching_keys_for_target_id", [&]() {
TargetData target_data = MakeTargetData(query_rooms_);
cache_->AddTarget(target_data);
TargetId target_id = target_data.target_id();
std::string key = LevelDbTargetKey::Key(target_id);
leveldb_persistence()->current_transaction()->Delete(key);

auto result = cache_->GetTarget(query_rooms_.ToTarget());
ASSERT_EQ(result, absl::nullopt);
});
}

} // namespace local
} // namespace firestore
} // namespace firebase